RegEx with \d doesn’t work in if-else statement with [[

i wrote the following script. It will be used in a build process later. My goal is to decide whether it's a pre release or a release. To archive this i compare $release to a RegEx. If my RegEx matches it's a pre release, if not it's a release.

#/bin/bash
release="1.9.2-alpha1"
echo "$release"
if [[ "$release" =~ \d+\.\d+\.\d+[-]+.* ]];then
echo "Pre"
else
echo "Release"
fi

But as result i always end up with the following:

~$ bash releasescript.sh
1.9.2-alpha1
Release

Version:

Ubuntu 18.04.1 LTS

I used this editor to test my RegEx. I'm stuck for at least 6h, so i would appreciate some help greatly.

Solution 1:

\d and \w don't work in POSIX regular expressions, you could use [[:digit:]] though

#/bin/bash
release="1.9.2-alpha1"
echo "$release"
LANG=C # This needed only if script will be used in locales where digits not 0-9
if [[ "$release" =~ ^[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+-+ ]];then
echo "Pre"
else
echo "Release"
fi

I have tested this script, it output "Pre" for given $release

Checked out your regex builder, it works only with perl compatible and javascript regex, while you need posix, or posix extended.

By @dessert:

[0-9] is the shorter alternative to [[:digit:]]. As the beginning of the string is to be matched, one should add ^, while .* at the end is superfluous: ^[0-9]+\.[0-9]+\.[0-9]+-+ – using a group this can be further shortened to: ^([0-9]+\.){2}[0-9]+-+